The growing body of evidence that marijuana, also known as cannabis, could be effective as a pain reliever has been expanded with publication of a new study in The Journal of Pain. The study reported that patients with nerve pain showed reduced pain intensity from smoking marijuana.

Researchers at University of California Davis evaluated whether marijuana produces analgesia for patients with neuropathic pain. For this, 38 patients were examined and given high-dose (7%), low-dose (3.5%), or placebo cannabis.

It was reported by the authors that identical levels of analgesia were produced at each cumulative dose level by both concentrations of the agent and cannabis reduced the core component of nociception and the emotional aspect of the pain experience to an equal degree.

The authors noted that a case could be made for testing lower concentrations to determine if the analgesic profile can be maintained while reducing potential cognitive decline, since high and low dose cannabis produced equal analgesic efficacy. The authors added that further research could probe whether adding the lowest effective dose of cannabis to another analgesic drug might lead to more effective neuropathic pain treatment for patients who otherwise are treatment-resistant.

The Food and Drug Administration (FDA), Substance Abuse and Mental Health Services Administration (SAMHSA), and the National Institute for Drug Abuse (NIDA) report that no sound scientific studies support the medicinal use of cannabis. Despite this lack of scientific validation, many patients routinely use “medical marijuana,” and in many cases this use is for pain related to nerve injury. We conducted a double-blinded, placebo-controlled, crossover study evaluating the analgesic efficacy of smoking cannabis for neuropathic pain. Thirty-eight patients with central and peripheral neuropathic pain underwent a standardized procedure for smoking either high-dose (7%), low-dose (3.5%), or placebo cannabis. In addition to the primary outcome of pain intensity, secondary outcome measures included evoked pain using heat-pain threshold, sensitivity to light touch, psychoactive side effects, and neuropsychological performance. A mixed linear model demonstrated an analgesic response to smoking cannabis. No effect on evoked pain was seen. Psychoactive effects were minimal and well-tolerated, with some acute cognitive effects, particularly with memory, at higher doses. PERSPECTIVE: This study adds to a growing body of evidence that cannabis may be effective at ameliorating neuropathic pain, and may be an alternative for patients who do not respond to, or cannot tolerate, other drugs. However, the use of marijuana as medicine may be limited by its method of administration (smoking) and modest acute cognitive effects, particularly at higher doses.